package main

import "fmt"
import "time"
import "flag"

//代码来自The go programming language

var period = flag.Duration("period",1*time.Second, "sleep period")
func f_7_4() {
	flag.Parse()
	fmt.Printf("sleeping for %v...", *period)
	time.Sleep(*period)
	fmt.Println()
}

func main() {
	f_7_4()
}